1. Field of the Invention
The present invention relates to an ink, an ink-jet recording method, and an ink cartridge, which can be used for ink-jet favorably.
2. Description of the Related Art
In the case where recording is performed on the surface of a recording medium with an ink-jet ink containing a pigment, a state in which much of the pigment and a polymer used as a dispersing agent are present on the surface of the recording medium is brought about depending on the recording medium used. Consequently, there is a problem in that degradation in glossiness of an image occurs easily. For example, regarding a swelling type recording medium, which is one type of recording media frequently used for an ink-jet recording method, no pore is present in an ink-receiving layer. Regarding a void type recording medium, pores are present in the ink-receiving layer, although the average particle diameter of a pigment particle is larger than the pore diameter. Consequently, most of the applied pigment particles do not permeate into the ink-receiving layer of the recording medium and is present on the surface of the recording medium through deposition. As a result, an image formed by an ink comes into the state, in which a new surface has been formed by the pigment deposited on the surface of the recording medium. Furthermore, in the case where the ink containing the polymer is applied to the recording medium and, thereafter, the concentration of the polymer relatively increases through evaporation of water and the like, agglomeration of the polymer proceeds, so that more polymers remain on the surface of the recording medium. Degradation in smoothness of the image surface and degradation in glossiness of the image may occur depending on the state of the pigment and the polymer present on the surface of the recording medium through deposition, the state being brought about as described above.
In consideration of the above-described issues, there is a proposal in which carbon black particles having a low level of structure are used as coloring materials for a black ink, the carbon black is deposited on the surface of the recording medium relatively smoothly and, thereby, the glossiness of the image is improved (refer to Japanese Patent Laid-Open No. 2002-097390). However, the carbon black particles having the low level of structure, that is, exhibiting a small DBP oil absorption, have very small particle diameters. Consequently, there is another problem in that it is difficult to disperse into an aqueous medium stably and the storage stability of the ink is insufficient. In consideration of this issue, there is a proposal in which an urethane polymer having a low acid value is further contained in the ink, so that the storage stability of the ink is improved and, in addition, the water resistance of the resulting image is improved (refer to Japanese Patent Laid-Open No. 2004-285344). Moreover, there is a proposal in which at least one of a polymer and a water-soluble functional group is bonded to the surface of carbon black particle (refer to PCT Japanese Translation Patent Publication No. 2010-516860 and Japanese Patent Laid-Open No. 2000-095987).